Preventive measures to prevent multimeter pointer from bending and meter head from being burned
When using a multimeter, improper operation can cause the pointer to bend, and in severe cases, it can burn out the meter head.
To prevent such accidents from occurring, pay attention to the following when using a multimeter:
1) Before measuring, estimate the size of the object being measured and turn the range switch to the appropriate range gear.
If you are not sure about the size being measured, you can first set the range to the maximum gear, and then slowly move towards the appropriate range gear.
Note that when measuring large objects with a small range, it is highly likely that the pointer will bend.
2) When measuring resistance, the tested circuit must be disconnected from the power supply.
3) Do not rotate the range switch when testing high voltage or high current. To prevent arcing at the contacts and damage to the switch.
4) When measuring electrolytic capacitors, first short-circuit and discharge them before measuring.
5) When using a multimeter incorrectly, the header may be burned.
Preventive measures: Connect two silicon diodes in parallel at the positive and negative ends of the meter head for protection (one in forward parallel and one in reverse parallel).
The conduction voltage of a silicon diode is generally greater than 0.5V, and below 0.5V, the forward resistance of the silicon diode is large, which has a small impact on the original internal resistance of the meter head and can be basically ignored.
When there is a false measurement, the increase in voltage will cause the forward resistance of the silicon diode to decrease, and most of the current will be diverted by the diode, which serves to protect the meter head.
